lighthouse/core/lib/navigation-error.js

Automated auditing, performance metrics, and best practices for the web.

/**
 * @license
 * Copyright 2021 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import * as Lantern from './lantern/lantern.js';
import {LighthouseError} from './lh-error.js';
import {NetworkRequest} from './network-request.js';
import * as i18n from '../lib/i18n/i18n.js';

const UIStrings = {
  /**
   * Warning shown in report when the page under test is an XHTML document, which Lighthouse does not directly support
   * so we display a warning.
   */
  warningXhtml:
    'The page MIME type is XHTML: Lighthouse does not explicitly support this document type',
  /**
   * @description Warning shown in report when the page under test returns an error code, which Lighthouse is not able to reliably load so we display a warning.
   * @example {404} errorCode
   */
  warningStatusCode: 'Lighthouse was unable to reliably load the page you requested. Make sure' +
    ' you are testing the correct URL and that the server is properly responding' +
    ' to all requests. (Status code: {errorCode})',
};

const str_ = i18n.createIcuMessageFn(import.meta.url, UIStrings);

// MIME types are case-insensitive but Chrome normalizes MIME types to be lowercase.
const HTML_MIME_TYPE = 'text/html';
const XHTML_MIME_TYPE = 'application/xhtml+xml';

/**
 * Returns an error if the original network request failed or wasn't found.
 * @param {LH.Artifacts.NetworkRequest|undefined} mainRecord
 * @param {{warnings: Array<string | LH.IcuMessage>, ignoreStatusCode?: LH.Config.Settings['ignoreStatusCode']}} context
 * @return {LH.LighthouseError|undefined}
 */
function getNetworkError(mainRecord, context) {
  if (!mainRecord) {
    return new LighthouseError(LighthouseError.errors.NO_DOCUMENT_REQUEST);
  } else if (mainRecord.failed) {
    const netErr = mainRecord.localizedFailDescription;
    // Match all resolution and DNS failures
    // https://cs.chromium.org/chromium/src/net/base/net_error_list.h?rcl=cd62979b
    if (
      netErr === 'net::ERR_NAME_NOT_RESOLVED' ||
      netErr === 'net::ERR_NAME_RESOLUTION_FAILED' ||
      netErr.startsWith('net::ERR_DNS_')
    ) {
      return new LighthouseError(LighthouseError.errors.DNS_FAILURE);
    } else {
      return new LighthouseError(
        LighthouseError.errors.FAILED_DOCUMENT_REQUEST, {errorDetails: netErr});
    }
  } else if (mainRecord.hasErrorStatusCode()) {
    if (context.ignoreStatusCode) {
      context.warnings.push(str_(UIStrings.warningStatusCode, {errorCode: mainRecord.statusCode}));
    } else {
      return new LighthouseError(LighthouseError.errors.ERRORED_DOCUMENT_REQUEST, {
        statusCode: `${mainRecord.statusCode}`,
      });
    }
  }
}

/**
 * Returns an error if we ended up on the `chrome-error` page and all other requests failed.
 * @param {LH.Artifacts.NetworkRequest|undefined} mainRecord
 * @param {Array<LH.Artifacts.NetworkRequest>} networkRecords
 * @return {LH.LighthouseError|undefined}
 */
function getInterstitialError(mainRecord, networkRecords) {
  // If we never requested a document, there's no interstitial error, let other cases handle it.
  if (!mainRecord) return undefined;

  const interstitialRequest = networkRecords.find(record =>
    record.documentURL.startsWith('chrome-error://')
  );
  // If the page didn't end up on a chrome interstitial, there's no error here.
  if (!interstitialRequest) return undefined;

  // If the main document didn't fail, we didn't end up on an interstitial.
  // FIXME: This doesn't handle client-side redirects.
  // None of our error-handling deals with this case either because passContext.url doesn't handle non-network redirects.
  if (!mainRecord.failed) return undefined;

  // If a request failed with the `net::ERR_CERT_*` collection of errors, then it's a security issue.
  if (mainRecord.localizedFailDescription.startsWith('net::ERR_CERT')) {
    return new LighthouseError(LighthouseError.errors.INSECURE_DOCUMENT_REQUEST, {
      securityMessages: mainRecord.localizedFailDescription,
    });
  }

  // If we made it this far, it's a generic Chrome interstitial error.
  return new LighthouseError(LighthouseError.errors.CHROME_INTERSTITIAL_ERROR);
}

/**
 * Returns an error if we try to load a non-HTML page.
 * Expects a network request with all redirects resolved, otherwise the MIME type may be incorrect.
 * @param {LH.Artifacts.NetworkRequest|undefined} finalRecord
 * @return {LH.LighthouseError|undefined}
 */
function getNonHtmlError(finalRecord) {
  // If we never requested a document, there's no doctype error, let other cases handle it.
  if (!finalRecord) return undefined;

  // If the document request error'd, we should not complain about a bad mimeType.
  if (!finalRecord.mimeType || finalRecord.statusCode === -1) return undefined;

  // mimeType is determined by the browser, we assume Chrome is determining mimeType correctly,
  // independently of 'Content-Type' response headers, and always sending mimeType if well-formed.
  if (finalRecord.mimeType !== HTML_MIME_TYPE && finalRecord.mimeType !== XHTML_MIME_TYPE) {
    return new LighthouseError(LighthouseError.errors.NOT_HTML, {
      mimeType: finalRecord.mimeType,
    });
  }

  return undefined;
}

/**
 * Returns an error if the page load should be considered failed, e.g. from a
 * main document request failure, a security issue, etc.
 * @param {LH.LighthouseError|undefined} navigationError
 * @param {{url: string, ignoreStatusCode?: LH.Config.Settings['ignoreStatusCode'], networkRecords: Array<LH.Artifacts.NetworkRequest>, warnings: Array<string | LH.IcuMessage>}} context
 * @return {LH.LighthouseError|undefined}
 */
function getPageLoadError(navigationError, context) {
  const {url, networkRecords} = context;
  /** @type {LH.Artifacts.NetworkRequest|undefined} */
  let mainRecord = Lantern.Core.NetworkAnalyzer.findResourceForUrl(networkRecords, url);

  // If the url doesn't give us a network request, it's possible we landed on a chrome-error:// page
  // In this case, just get the first document request.
  if (!mainRecord) {
    const documentRequests = networkRecords.filter(record =>
      record.resourceType === NetworkRequest.TYPES.Document
    );
    if (documentRequests.length) {
      mainRecord = documentRequests.reduce((min, r) => {
        return r.networkRequestTime < min.networkRequestTime ? r : min;
      });
    }
  }

  // MIME Type is only set on the final redirected document request. Use this for the HTML check instead of root.
  let finalRecord;
  if (mainRecord) {
    finalRecord = Lantern.Core.NetworkAnalyzer.resolveRedirects(mainRecord);
  } else {
    // We have no network requests to process, use the navError
    return navigationError;
  }

  if (finalRecord?.mimeType === XHTML_MIME_TYPE) {
    context.warnings.push(str_(UIStrings.warningXhtml));
  }

  const networkError = getNetworkError(mainRecord, context);
  const interstitialError = getInterstitialError(mainRecord, networkRecords);
  const nonHtmlError = getNonHtmlError(finalRecord);

  // We want to special-case the interstitial beyond FAILED_DOCUMENT_REQUEST. See https://github.com/GoogleChrome/lighthouse/pull/8865#issuecomment-497507618
  if (interstitialError) return interstitialError;

  // Network errors are usually the most specific and provide the best reason for why the page failed to load.
  // Prefer networkError over navigationError.
  // Example: `DNS_FAILURE` is better than `NO_FCP`.
  if (networkError) return networkError;

  // Error if page is not HTML.
  if (nonHtmlError) return nonHtmlError;

  // Navigation errors are rather generic and express some failure of the page to render properly.
  // Use `navigationError` as the last resort.
  // Example: `NO_FCP`, the page never painted content for some unknown reason.
  // Note that the caller possibly gave this to us as undefined, in which case we have determined
  // there to be no error with this page load - but there was perhaps a warning.
  return navigationError;
}

export {
  getNetworkError,
  getInterstitialError,
  getPageLoadError,
  getNonHtmlError,
  UIStrings,
};